1. Field of the Invention
This invention relates to the field of dust collection devices. More particularly, this invention relates to the field of self-cleaning and self-emptying collectors for dust generated by the drilling of bolt holes in mine ceilings.
2. Description of the Prior Art
In underground mining situations, it is frequently desired to place a plurality of expansion bolts into the mine ceiling for support. The placement of bolts requires that appropriate holes be drilled in the roof as a preparatory step. This drilling operation creates large quantities of dust which can make working conditions within the mine intolerable and unhealthy, particularly so for the drill operator.
For these reasons, devices have been developed to carry the dust generated by drilling away from the drill site, where the drill operator is positioned. Typically, such devices comprise a hollow drill rod with at least one hole therein adjacent the drill bit, which drill rod communicates with some type of suction device, such as a venturi, having an outlet at a point remote from the drill operator.
Devices have further been developed to filter the air sucked away from the drill site before returning it to the mine environment. These devices have frequently been of the single stage type, such as, for instance, a chamber having a plurality of baffle plates therein over which the dust-laden air passes. In such collectors, the dust impinges upon the baffle plates and is thus removed from the air stream which flows back into the open air.
It has become known that multi-stage filtering devices are more effective than their single-stage counterparts, and such devices have been developed to filter out and collect the dust generated by roof drilling operations. The Donaldson Company, Inc., Series RDX00-4545 roof drill dust collector is an example of such a device.
Up until the time of the present invention, however, even such multi-stage units have not proved entirely satisfactory. The primary cause of dissatisfaction has stemmed from the fact that such units have a limited dust storage capacity. This means that a drill operator using a conventional collector has to determine how many holes he can drill before his dust collector is full, and he must then keep track of the number of holes drilled as he goes along, stopping to manually empty the dust collector when it is full. This not only means that he must leave the drilling site, thus losing drill time, but also means that he must expose himself to the clouds of dust he has been trying to avoid, by manually dumping the dust from the collector to the mine floor.
No prior art devices known to the inventor combine an air cleaning device, particularly a multi-stage air cleaning device, with means for automatically cleaning the device and emptying collected dust from the device.